Liquid gun propellants and rocket propellants based on concentrated water solutions of hydroxylammonium nitrate (HAN) as the oxidizer and another solid or fluid material as the fuel are known. For example, U.S. Pat. No. 4,402,775, issued to Wood on Sept. 6, 1983, column 1, teaches a liquid gun bipropellant comprising HAN and a hydrocarbon fuel, mixed in the gun. Wood states that this composition requires more than 10 parts of HAN for each part of fuel. Triethanolammonium nitrate fuels for aqueous solution HAN-based monopropellants are also known. It would be useful to provide a more energetic fuel with a higher impetus and burn rate than these propellants have.
Cubane is a coined name for pentacyclo[4.2.0.0.sup.2,5.-0.sup.3,8.0.sup.4,7 ]octane. In the 1,4 orientation of substituents of cubane, the two substituents are attached to diametrically opposed corners of the cubic nucleus. All disubstituted cubanes referred to herein are 1,4-cubanes.
Various salts and compounds of cubane are known. Eaton, et al., "Synthesis of 1,4-dinitrocubane", Journal of Organic Chemistry, Vol. 49, No. 1, pages 185-186 (1984), and U.S. Pat. No. 3,558,704, issued to Gregory on Jan. 26, 1971, discloses the following compounds:
1,4-dinitrocubane (CAS Registry No. 87830-30-6); nitroperchlorohomocubane; PA0 cubane-1,4-dicarboxylic acid (CAS Registry No. 32846-66-5); PA0 1,4-diaminocubane (CAS Registry No. 87830-29-3); PA0 1,4-bis[(tertiarybutoxycarbonyl)amino]cubane (CAS Registry No. 87830-27-1); PA0 1,4-diaminocubane dihydrochloride (CAS Registry No. 87830-28-2); PA0 4-methylcubane-1-amine; PA0 4-methylcubane-1-methylamine
The first paragraph of the cited Eaton article suggests that 1,4-dinitrocubane is contemplated to have good thermal stability and high density, and to be an "energetic" compound, but the article does not show the energetics of that compound or other properties relevant to its use in a propellant. On page 186, column 2, the Eaton reference contains a synthesis of 1,4-diaminocubane dihydrochloride from 1,4-bis[tertiarybutoxycarbonyl)amino]cubane, and the synthesis of the latter compound from cubane-1,4-dicarboxylic acid. The reference indicates that cubane-1,4-dicarboxylic acid is available in substantial quantities from the University of Chicago, and cites Eaton et al., Journal of the American Chemical Society, Vol. 86, page 962 (1964) for a synthesis of cubane-1,4-dicarboxylic acid. Cubane 1,4-dicarboxylic acid is commercially available in the form of the dimethyl ester, from Enichem Sintesi SpA., Milan, Italy.
None of the synthetic methods in the prior art known to the present inventors involve the use of anionic exchange resins, and no utility is disclosed for any of the compounds listed above, excepting the nontoxic acid addition salts of 4-methylcubane-1-amine and 4-methylcubane-1-methylamine, which are disclosed to be antiviral agents in animals.